Transcript GEM - Florida Institute of Technology
A First Application for the Scalable Readout System:
Muon Tomography with GEM Detectors
RD51 Collaboration Meeting
WG5 - May 25, 2010
Marcus Hohlmann with Kondo Gnanvo, Lenny Grasso, J. Ben Locke, and Amilkar Quintero
Florida Institute of Technology, Melbourne, FL, USA
Q=+26e
μ
Muon Tomography Principle
Incoming muons ( μ ± )
(from natural cosmic rays)
Note: angles are exaggerated !
Q=+92e
μ 56 26 Fe Regular material: small scattering angles
Θ Θ
hidden & shielded high-Z nuclear material
Θ
μ 235 92 U
Θ
HEU: Big scattering angles!
Approx. Gaussian distribution of scattering angles θ with width θ
0
:
Main ideas:
μ tracks
0 13 .
6 MeV
cp x X
0 [ 1 0 .
038 ln(
x
/
X
0 )] with 1
X
0
Z
(
Z
1 ) • • • •
Multiple Coulomb scattering is ~ prop. to Z and could discriminate materials by Z Cosmic ray muons are ubiquitous; no artificial radiation source or beam needed Muons are highly penetrating; potential for sensing shielded high-Z nuclear contraband Cosmic Ray Muons come in from many directions allowing for tomographic 3D imaging
5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 2
Fl. Tech Concept: MT w/ MPGDs
Use M icro P attern G aseous D etectors for tracking muons μ tracks ADVANTAGES:
small detector structure allows compact, low-mass MT station
• • •
thin detector layers small gaps between layers low multiple scattering in detector itself
high MPGD spatial resolution (~ 50
m) provides good scattering angle measurement with short tracks
high tracking efficiency
hidden & shielded high-Z nuclear material
Θ
μ Small triple-GEM under assembly GEM Detector
Θ
MPGD, e.g. GEM Detector CHALLENGES:
need to develop large-area MPGDs
large number of electronic readout channels needed (→ SRS) G as E lectron M ultiplier Detector ~ 1.5 cm
e 5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 3
General Strategy
• Build
first prototype
of GEM-based Muon Tomography station & evaluate performance (using ten 30cm 30cm GEM det.) – Detectors – Mechanics – Readout Electronics → SRS !
– HV & Gas supply – Data Acquisition & Analysis • Help develop
large-area (1m
electronics
within RD51
0.5m) Triple-GEMs and SRS
• Build
final 1m
1m
1m GEM-based
Muon Tomography prototype station • Measure
performance
with both prototypes on shielded targets and “vertical clutter” 5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
2.
1.
Two-pronged approach:
2009/10 Strategy
Build and operate minimal
first GEM-based Muon Tomography station: – – – – only four Triple-GEM detectors (two at top and two at bottom) temporary GASSIPLEX electronics (~800 ch., borrowed from Saclay – THANKS !!!) minimal coverage (read out only 5cm 5cm area in each detector) preliminary data acquisition system (LabView; modified from MAMMA – THANKS !!!) – • • •
Objectives: take real data as soon as possible and analyze
demonstrate that GEM detectors work as anticipated for cosmic ray muons → produce
very first experimental proof-of-concept for GEM MT Simultaneously prepare for
30cm 30cm 30cm Muon Tomography Station: – – – – Top, bottom, and side detectors (10 detectors) Mechanical stand with flexible geometry, e.g. variable gaps b/w detectors Final SRS front-end electronics (15,000 ch.) with RD51 Final data acquisition with RD51 & analysis M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 5/25/2010
•
Hardware Progress
Detector Assembly:
–
7
30cm 30cm Triple-GEM detectors assembled in CERN clean rooms – – –
1 2 2
30cm 30cm 10cm 30cm Double-GEM detector assembled in CERN clean rooms (b/c one foil was lost) 30cm Triple-GEM detectors awaiting assembly at Fl. Tech 10cm Triple-GEM detectors assembled at Fl. Tech (for R&D purposes) • •
Basic performance parameters
– HV stability, sparks – Gas gain – HV plateau – Rate capability – of triple-GEM detectors tested with X-rays and mips
:
55 Fe and mip (cosmics) pulse height spectra
=> Six Triple-GEM detectors at CERN show good and stable performance
One Triple-GEM detector has bad HV section; to be fixed •
Built minimal prototype station
for Muon Tomography;
operated 2 weeks at CERN
– Designed and produced adapter board for interfacing detector r/o board with Panasonic connectors to preliminary “GASSIPLEX” frontend electronics with SAMTEC connectors (Kondo Gnanvo) – Used 8 GASSIPLEX frontend r/o cards electronics with ~800 readout channels for two tests (Dec ’09 - Jan ’10 and April ’10, Kondo Gnanvo) – Developed LabView DAQ system for first prototype tests – lots of debugging work (Kondo Gnanvo) • Developed GEANT4 simulation for minimal MT prototype station 5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
terminators
Triple-GEM Detector
On X-ray bench at GDD
768 y-strips Gas outlet Gas inlet 5/25/2010 HV sections High voltage board (voltage divider) Gate pulse for ADC Argon escape Triple-GEM pulses under 8 keV X-rays Photo peak Single channel meas. with ORTEC pre-amp HV input (4kV) M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
Basic Detector Performance
Results from commissioning test of Triple-GEM detectors using single-channel amp. & 8 kV Cu X-ray source at GDD
100000 70
Gas gain
10000
Gas gain vs. HV 2
10 4
X-ray rate [kHz] 60 50 40
MTGEM-7 Efficiency plateau Rate plateau Detector efficient
At this high voltage, the transfer gap becomes efficient for X-ray detection adding some pulses from the “double-GEM” structure. (Not discharges !) 30 vertical strips 20
(lower threshold)
10 horizontal strips 1000 3600 3700 3800 3900 4000 Applied Chamber HV [V]
Applied Chamber HV [V]
4100 4200 0 3600 3800 4000 Applied Chamber HV [V] 4200 25 Anode current
vertical
20 strips [nA] 15 10
Pulse height spectra Mips (cosmic ray muons) 8 keV X-rays
5
Charge sharing b/w x- and y-strips Argon escape peak
0 0 5/25/2010 5 10 15 Anode current – 20
horizontal
25 30 strips [nA] M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
Pulse height distribution
Landau Fit Minimum Ionizing Particles (Cosmic Ray Muons) [ADC counts]
Distribution of total strip cluster charge follows Landau distribution as expected 5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
Minimal MT Station
Setup of first cosmic ray muon run at CERN with four Triple-GEM detectors Event Display: Tracking of a cosmic ray muon traversing minimal GEM MT station Top 1 Top 2 Bottom 1 Bottom 2 3-GEM Top 1 3-GEM Top 2 Pb target 3-GEM Bottom 1 Preliminary Electronics (GASSIPLEX)
5/25/2010
FIT interface board 3-GEM Bottom 2
• • •
Strip Position [mm] Pulse heights on x-strips and y-strips recorded by all 4 GEM detectors using preliminary electronics and DAQ Pedestals are subtracted No target present; Data taken 4/13/2010
M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
y x
First Data: Strip Clusters
Sharing of deposited charge
among adjacent strips is important for high spatial resolution by using the center-of-gravity of charge deposition when calculating the hit position:
All recorded strip clusters centered on highest bin & added together Width of Gaussian fit to 855 measured individual strip clusters
=> Charge is shared between up to 5 strips 5/25/2010 => On the average, strip cluster is 3.2 strips wide ( 1 ) M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
MT Targets
5/25/2010 triggered triggered M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany triggered 12
Minimal MTS with Pb target
Event recorded with Pb target present in center of minimal MTS:
5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
Hits & Tracking
Empty Station
Real Data X-Z projection
Station with Pb target
Y-Z projection 5/25/2010 X-Z projection M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany Y-Z proj.
14
Basic Scattering Reconstruction
• Simple 3D reconstruction algorithm using 3-D tracks
Point of Closest Approach
(POCA) of incoming and exiting • Treat as
single scatter
• Scattering angle:
μ track direction
Scattering Object MT station Scattering angle 5/25/2010 (with >0 by definition) M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 15
Muon Tomography with GEMs !
First-ever experimental GEM-MT Data empty Fe Nominal target position Muons reconstructed:
Empty Fe Pb Ta 558 809 1091 1617
It works !!!
Pb Ta Mean scattering angles
in x
y
z = 2mm
2mm
20mm voxels (x-y slices taken at z = 0mm)
5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
Empty <
> [deg]
MT Front View (x-z)
Fe <
> [deg] Pb <
> [deg] Ta <
> [deg] Imaging in the vertical not as good as imaging in x-y because triggered muons are close to vertical
5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 17
Empty
3D Target Imaging
Fe Pb Ta
[deg]
5/25/2010
Scattering points (POCA) colored according to measured scattering angle (Points with
< 1 o are suppressed for clarity)
M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 18
Comparison Data vs. MC
empty Data Fe Monte Carlo (~ 20 times data) empty Fe Pb Nominal target position Ta Pb Ta Mean scattering angles
in x
y
z = 2mm
2mm
20mm voxels (x-y slices taken at z = 0mm)
5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
Comparison Data vs. MC cont’d
5/25/2010
Empty Fe
Only data for which the POCA is reconstructed
within
the MTS volume are used for comparison.
For measurements at small angles ( < 1 o ), MC and data do not agree that well, yet.
Pb Ta
This is presumably due to: • the fact that the GEM detectors in the MTS have not yet been aligned with tracks.
For now, we are solely relying on mechanical alignment.
Any
mis
alignment
increases
the angle measurement because the scattering angle is by definition positive.
• the fact that the GEANT4 description of the materials used in the station itself is not yet perfect M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 20
Next steps…
5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 21
30cm
30cm
30cm Prototype
?
Planned Geometry & Mechanical Design: 31.1cm
31.7cm
?
Maximizes geometric acceptance
GEM detector active area 5/25/2010 Target plate
All designs by Lenny Grasso; under construction at Fl. Tech
M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
5/25/2010
30cm
30cm
30cm Prototype
APV25 readout chip
• originally developed for CMS Si-strip detector by ICL • production in 2003/04 • yield of 120,000 good chip dies •
128 channels/chip
• preamplifier/shaper with 50ns peaking time • 192-slot buffer memory for each channel • multiplexed analog output • integrated test pulse system • runs at 40 MHz • used e.g. by CMS, COMPASS, ZEUS, STAR, Belle experiments
MOST IMPORTANT:
• Chip is still available • “Cheap” ! (CHF28/chip) HEP group, Imperial College, London
We have procured 160 chips
for our ten 30cm × 30cm detectors (min. 120 needed) M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
APV 25
Front-end hybrid card
Diode protection for chip Connector to chamber
•
128 channels/hybrid
• Integrated diode protection against sparks in GEM detector • Estimated cost: EUR55/card • Plan to get 160 cards for MT • 8 Prototype boards made at CERN •
First on-detector tests
performed with MT-GEMs at CERN by Sorin, Hans, Kondo (→ Sorin’s next talk): 5/25/2010 HM M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany HM
30cm
30cm
30cm Prototype
Electronics & DAQ under development Est. cost per electronics channel: $1-2
5/25/2010
Prototypes of basically all components exist by now and are under test at CERN by RD51 electronics group
M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
Plans for 2
nd
half of 2010
1.
2.
3.
• • •
Analyze data for minimal station
Measure performance: resolution, efficiency, muon tomography Test other reconstruction methods (EM, Clustering) besides POCA on real data Publish results • • • • • • •
Build & operate 30cm
30cm
30cm MT prototype with SRS
Help develop DAQ for SRS ( → software!) Commission all GEM detectors with final SRS electronics & DAQ at CERN Develop offline reconstruction Get experimental performance results on muon tracking Take and analyze lots of Muon Tomography data at CERN Test performance with shielded targets in various configurations Ship prototype to Florida and install in our lab; continue MT tests there • •
Development of final 1m
1m
1m MT station
Prepare for using large-area GEM foils (~100cm 50cm): Adapt thermal stretching technique to large foils Try to simplify construction technique: Build small Triple-GEM detectors without stretching GEM foils (using our standard CERN 10cm 10cm detectors, going on now) M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 5/25/2010 26
Towards 1m
1m
1m MT station New infrastructure for stretching GEM foils:
• Thermal stretching method (plexiglas frame) • Heating with infrared lamps (40-80 o C) • On flat metallic optical bench ( = heat bath) • Everything inside large mobile clean room • Potentially scalable to 1-2 m for large GEMs New grad students: Mike & Bryant 2m optical bench 5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 27
Funding situation
•
Good news:
– Substantial progress with hardware in 2009/10 and
strong support from RD51
have convinced Dept. of Homeland Security to continue project for one more year – Funding action for June ’10 – May ’11 in progress – Funds for full SRS readout system (15k ch.) for “cubic-foot” station expected to be available in ‘10 – Continuing to fund post-doc (Kondo) and one grad student (Mike) to work on project M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 5/25/2010 28
A big
Acknowledgments
to RD51:
5/25/2010 – Rui, Miranda for support w/ building the detectors – Esther, Fabien, Maxim , (Saclay) for lending us the GASSIPLEX cards
– twice…
– Theodoros (Demokritos) & MAMMA started on the LabView DAQ system for getting us – Leszek, Serge, Marco & Matteo (GDD) for all the help with setting up various tests in the GDD lab – Hans & Sorin for all the design, development, and testing work on the SRS M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 29
Backup Slides
Triple-GEM design
} Top honeycomb plate } Drift cathode and spacer Follows original development for COMPASS exp.
& further develop ment for TERA } } } 3 GEM foils stretched & glued onto frames/spacers } 2D Readout Foil with ~1,500 strips } Bottom honeycomb base plate 5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany 31
Minimal MT station
Setup at GDD in April 2010
5/25/2010 M. Hohlmann, Florida Institute of Technology - RD51 Coll. Meeting, Freiburg, Germany
Beyond FY10…
Large photosensitive GEM Detector (100-200 keV
’ s) ?
( , X-ray, charged particles)
Muon Tomography with integrated
-detection ?
Fl. Tech – U. Texas, Arlington planned joint effort (Physics & Material Science Departments)